Hello All I am new to this sport, and have been working on a vintage Rupp American 1973.
I dont understand much about carbs, but I removed and cleaned her up, and the sled now fires, and stays running but boggs down when given throttle. I imagine I have to adjust the carb settings, but dont know the diffenrence of the three screws on the side of the Kei Hin carb ive got. It has a circular bowl on the bottom with a screw that I imagine adjusts the pump diaphram. There is a long needle shaped component that sits in the middle hole with a small T handle on it and spring behind. Can anyone tell me what screws do what and their respective adjustment?
Thanks, I know we all had to ask these questions at one point....
Vern

Vern I've got a picture of a Keihin carb but I only see two adjusting screws. The one closest to the carb intake is the HIGH speed needle and the one in the middle of the carb is the IDLE needle.The book says 1 1/4 turns open for Idle mixture screw and one turn open for HIGH speed mixture screw. This carb has a sight tube that lets you check fuel level.

Hope this helps.